A patent literature 1 discloses a display device including organic EL elements (see FIG. 16). This conventional display device includes (i) control lines DSL, AZL1, AZL2, and WSL, (ii) signal lines DTL, and (iii) power supply lines Vofs, Vss, Vcc, and Vcat. In the display device, an organic EL element 1, five n-channel transistors T1 through T5, and a capacitor C1 are provided in each pixel 10. Note, here, that (i) a gate terminal of the transistor T1 is connected to the control line WSL, (ii) a gate terminal of the transistor T2 is connected to the control line AZL2, (iii) a gate terminal of the transistor T3 is connected to the control line DSL, (iv) a gate terminal of the transistor T4 is connected to the control line AZL1, (v) a gate terminal of the transistor T5 (drive transistor) is connected to the signal line DTL via the transistor T1 and to the power supply line Vofs via the transistor T2, (vi) a drain terminal of the transistor T5 is connected to Vcc via the transistor T3, (vii) a source terminal of the transistor T5 is connected to an anode of an organic EL element and to Vss via the transistor T4, (viii) the capacitor C1 is provided between a gate terminal and a source terminal of the transistor T5, and (ix) a cathode of the organic EL element is connected to the power supply line Vcat.
The pixel circuit 10 is arranged in which (i) an anode electric potential of the organic EL element 1 is subjected to initialization and a threshold value of the transistor T5 is detected (the threshold value of the transistor T5 is stored between the gate terminal and the source terminal of the transistor T5), and (ii) a data signal electric potential is written into the gate terminal of the transistor T5 via the transistor T1 so that a current flows through the organic EL element 1 via the transistors T3 and T5 (so that the organic EL element 1 emits light). This arrangement can correct a possible increase in resistance caused by the threshold value of the transistor T5 and deterioration of the organic EL element.
The patent literature 1 discloses an arrangement that one wiring line is used so as to serve as both the power supply line Vofs connected to the transistor T2 and the control line WSL. A patent literature 2 discloses an arrangement that one wiring line is used to serve as both a control line AZL2 of a given horizontal pixel row and a control line WSL of another horizontal pixel row followed by the given horizontal pixel row. A patent literature 3 discloses an arrangement that one wiring line is used so as to serve as both a power supply line Vss connected to a transistor T4 and a power supply line Vofs connected to a transistor T2, and an electric potential that is being supplied via the signal line during each period is switched from one to another.